This study examined the collaborative development of a comprehensive school-based intervention (CSBI) and component feasibility for seven children, aged 7 to 8 years, with high-functioning autism spectrum disorders (HFASDs). In Phase I, focus groups were conducted in two school districts with school staff and/or parents of children with HFASDs. The focus groups examined needs, resources, and barriers related to CSBIs, followed by adaptation of an empirically supported nonschool psychosocial intervention for HFASDs into a CSBI manual. In Phase II, two 4-week component trials examined the feasibility of the five treatment components when administered by school staff. Focus-group meetings were also held during Phase II to revise the CSBI manual as needed. Feasibility was assessed according to the level of treatment fidelity during implementation and teacher- and parent-reported acceptability and satisfaction. Feasibility was supported in high levels of treatment fidelity and teacher- and parent-reported acceptability and satisfaction.